Hi,A relative of mine went for an angiogram because he has some chest pains. The cardiologist discovered that 2 coronary arteries has 75% blockage. However, the cardiologist is more concerned that the Left Internal Mammary Artery has a 95% blockage. The cardiologist is concerned that this might lead to a stroke and is consulting a neurologist because it is not his area of expertise. We have to wait till sometime next week for the result of this consultation.

What is the Left Internal Mammary Artery and why is the cardiologist concerned that it could lead to a stroke and not a heart attack? What is the implication if the LIMA is blocked or has insufficient flow?

We searched the internet and there is not much information about the implication of blockage in the LIMA. The impression I get from the internet is that the LIMA supplies blood to the chest and is harvested for use to bypass blocked coronary arteries as an alternative to the vein from the leg. Does this mean that it is not something critical?

Hi there -- The LiMA does supply the left upper chest/breast, has a decent bore to it considering how non-critical its purpose, and is often simply pulled over to help resupply an area of the heart instead of harvesting a vein. Its being blocked is fairly unremarkable, and since it's in the same plane as some of the coronary arteries it's unsurprising if some of them are narrowed that it would be as well. If it were to become totally occluded it might cause some chest pain due to claudication (crampting due to starving out of chest muscle tissue) but wouldn't be dangerous. How any any artery outside the brain being blocked could cause a stroke is a mystery to me. If it were a vein -- almost any vein -- it wouldn't be narrowed but could contain a clot, which could eventually lead to a stroke or pulmonary embolism, but the LiMA is an artery, and blocked arteries that don't service the brain itself (The one exception would be either carotid artery, as they are essentially the blood supply freeway to the brain, but are upstream from the LiMA). While its significant narrowing disqualifies it as a bypass option I can't see how it might contribute to a stroke unless an attempt were made to use it to bypass a narrowed LAD, which would be pointless anyway. It can't hurt to have someone else --most logically a vascular surgeon -- evaluate the potential harm of having the artery blocked, but it would seem there must be some sort of misunderstanding somewhere in the chain of this exam to need a neurologist involved simply because of the condition of the LiMA.

If you find out more, please share with us here. This is a puzzle for sure. We'd love to hear the outcome.